Fix uninitialized variable use in Effects.cpp

Initialize variable 'io' in
AudioFlinger::EffectBase::updatePolicyState.
Found by clang-tidy.

Bug: 152526318
Test: m
Change-Id: Ib8c71eaf83dc140874d3e65a094e52e36918160f
diff --git a/services/audioflinger/Effects.cpp b/services/audioflinger/Effects.cpp
index 8a65122..81815f8 100644
--- a/services/audioflinger/Effects.cpp
+++ b/services/audioflinger/Effects.cpp
@@ -212,7 +212,7 @@
     bool registered = false;
     bool doEnable = false;
     bool enabled = false;
-    audio_io_handle_t io;
+    audio_io_handle_t io = AUDIO_IO_HANDLE_NONE;
     uint32_t strategy;
 
     {